FIG. 1 is a cross-sectional diagram of a conventional split-gate trench MOSFET. This example can include substrate 01, epitaxial layer 02 on substrate 01, trench 03 in epitaxial layer 02, trench pad 04 in trench 03, and field plate 05 and gate 06 located in trench 03 and being separated from epitaxial layer 02 by trench pad 04. In addition, the split-gate trench MOSFET can include a body region, a source region, and a source electrode, and field plate 05 can be coupled with the source electrode. Due to the presence of the field plate at the bottom of trench 03, this kind of split-gate trench MOSFET may increase the depletion of epitaxial layer 02 to optimize the electric field distribution of the device, thereby reducing the on-resistance of the device while simultaneously ensuring the breakdown voltage.